改性凹凸棒土/纳米铁复合材料与微生物耦合去除地下水硝酸盐氮的研究

Removal of Nitrate from Groundwater by Coupling System Composed with Modified Attapulgite/Fe Nano Composites and Microorganisms

地下水是我国重要的饮用水源之一,国内部分地区地下水NO_3^--N含量超标,对人体健康造成潜在威胁.采用模拟装置考察改性凹凸棒土/纳米铁复合材料、反硝化细菌及其耦合体系对地下水NO_3^--N去除效果及脱氮产物的变化特征.结果表明,在模拟地下水溶解氧[ρ(DO)为0.3 mg/L]、温度(15℃)和黑暗环境下,50 mg改性凹凸棒土/纳米铁复合材料与50 mg/L NO_3^--N反应,7 d后NO_3^--N去除率为43.7%,其中63.6%的还原产物转化为NH_4^+-N,几乎无NO_2^--N生成,TN去除率为15.9%;反硝化细菌体系中,7 d后NO_3^--N去除率仅为9.7%,其中NO_2^--N占4.1%,几乎无NH_4^+-N生成,TN去除率为5.3%;在改性凹凸棒土/纳米铁复合材料-反硝化细菌耦合体系中,7 d后NO_3^--N去除率为80.6%,其中NH_4^+-N占33.2%、NO_2^--N占12.1%,TN去除率为35.2%.研究显示,模拟地下水环境下,改性凹凸棒土/纳米铁复合材料-反硝化细菌耦合体系对NO_3^--N去除效果最好,TN去除率高.

Groundwater is an important source of drinking water in China. However,nitrate levels are above the limits in some areas,posing a serious threat to human health. NO_3^--N removal efficiency and characteristics of reaction products in groundwater by modified attapulgite/Fe nano composites,denitrifying bacteria and its coupling system were studied using simulation experiments. The results showed that the NO_3^--N removal ratio of modified attapulgite/Fe nano composites was 43. 7% after 7 d( experimental conditions: 15 °C,DO 0. 3 mg/L,dark). 63. 6% of the product was NH_4^+-N,while few NO_2^--N was generated; 15. 9% TN was removed. As for denitrifying bacteria system,the removal rate of NO_3^--N was only 9. 7% after 7 days,and the product of NO_2^--N was 4. 1% with almost no NH_4^+-N generated; only 5. 3% TN was removed. NO_3^--N removal efficiency was 80. 6% after 7 days in the coupling system,and the product included 33. 2% NH_4^+-N and 12. 1% NO_2^--N; TN removal efficiency achieved 35. 2%. Therefore,the coupling system was the best method with the highest TN removal efficiency for NO_3^--N among these three methods.